Highly conformal thin films of metals and metal oxides with a thickness of 50 Å or less are attaining increased attention in the fabrication of electronic devices including microelectronics, and magnetic information storage. Typically, these films have been produced by chemical vapor deposition (CVD) and atomic layer deposition (ALD) methods. As component device (i.e., transistors) size shrinks and increased densities of component devices and circuits are patterned, there is considerable need for new types of organometallic precursor compounds that can lead to the fabrication of these types of films by either CVD or ALD methods.
Thermally stable metal amidinates have been used as candidates for producing highly conformal thin films of transition metals. These might be used in producing logic and memory devices. Exemplary metals employed for such metal amidinates include cobalt, vanadium, iron, and nickel.
Metal silicides derived from metals of Groups VIIb, VIII, IX, and X have been shown to be attractive compounds in the electronics field particularly in the manufacture of integrated circuits and micro-electronics. Interest in metal silicides is increasing as device scale-down progresses due to their good thermal and chemical stability, low electrical resistivity, wide processing window and their small lattice mismatch to the silicon crystal lattice, which allows the metal silicide to be grown epitaxially on silicon.
The following patents and articles are representative of organometallic compounds suited for producing conformal thin metal or metal oxide films by CVD and ALD and their use in the electronics industry.
U.S. Pat. No. 6,777,565 B2 and U.S. Pat. No. 6,753,245 B2 disclose the deposition of metal films using organometallic compounds having the formula (R1)mM(PR23)x where M is a metal selected from the group consisting of Group VIIb, VIII, IX, or X such as iron, cobalt, nickel, manganese rhodium and so forth. Metal silyl phosphites are also shown and examples include those of the formula H2M[(CH3)3SiOP(OC2H5)2]4, and M[(CH3)3SiOP(OCH3)2]5.
US 2002/0081381 discloses the formation of cobalt films by alternately reacting bis(acetylacetonato)cobalt with either hydrogen or silane in an ALD process. The cobalt can be used as a glue layer between copper and a diffusion barrier layer such as that from TiN, TaN, and WN to improve the adhesion.
US 2002/0016065 discloses the formation of metal-containing films using organometallic complexes in which the metal center is coordinated with chelating C,N-donor ligands. One of the complexes, illustrated in the Example, Co{C(SiMe3)2(C5H4N)}2, was used to form a cobalt film on a silicon substrate.
WO 2004/046417 A2 and Roy G. Gordon, et al., Alternate Layer Deposition of Transition Metals, Nature Materials, vol. 2, 749 (November 2003) disclose the formation of highly conformal thin films by ALD using metal amidinates as an organometallic precursor. Cobalt (II) bis (N,N′-diisopropylacetamidinate, bis(N,N′-tert-butylacetamidinato)manganese and lanthanum tris(N,N′-dissopropyl-2-tert-butylamidinate) are shown as precursors.